name: Build & Publish Docker Image

on:
  push:
    branches: [main]
    tags: ['v*']
  workflow_dispatch:

env:
  REGISTRY: gitea.siegeln.net
  IMAGE_NAME: ${{ gitea.repository }}

jobs:
  build-and-push:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Log in to Gitea container registry
        # Uses a personal access token (PAT) with write:package scope.
        # The default GITEA_TOKEN cannot push to the container registry.
        # Create the PAT under User Settings → Applications, add it as a repo
        # secret named REGISTRY_TOKEN, and (optionally) REGISTRY_USER if the
        # owning account differs from ${{ gitea.actor }}.
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ secrets.REGISTRY_USER || gitea.actor }}
          password: ${{ secrets.REGISTRY_TOKEN }}

      - name: Derive tags
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=branch
            type=ref,event=tag
            type=sha,format=short
            type=raw,value=latest,enable=${{ gitea.ref == 'refs/heads/main' }}

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          context: .
          push: true
          # Target: Raspberry Pi 5 (arm64). Runner is arm64 too, so this is native + fast.
          # amd64 is buildable locally via `docker build` on dev machines.
          platforms: linux/arm64
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          # Registry-based cache: uses the image registry itself for layer reuse.
          # Avoids the unreliable Gitea Actions cache HTTP backend.
          cache-from: type=registry,ref=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:buildcache
          cache-to: type=registry,ref=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:buildcache,mode=max